An oil seal structure for an internal combustion engine is known to include an oil seal fixing member which fixes an oil seal. Such oil seal structure is disclosed, for example, in JP2010-32021A which is hereinafter referred to as Reference 1.
The oil seal structure disclosed in Reference 1 includes a timing chain cover (cover member) made of resin, an oil seal and a metallic retainer. The timing chain cover is arranged at a lateral surface portion of a cylinder block (internal combustion engine body). The oil seal is press-fitted to a crankshaft which penetrates through the timing chain cover. The metallic retainer fixes the oil seal. In the aforementioned oil seal structure, the metallic retainer includes a flange portion provided around a bore portion into which the crankshaft is inserted to be positioned and a pair of mounting members (left and right mounting members) integrally provided at the flange portion. The pair of mounting members extends from left and right edge portions of the flange portion to left and right outer edge portions of the timing chain cover respectively as viewed in a direction where the crankshaft extends. The pair of mounting members is fastened together with the timing chain cover to the cylinder block at the left and right outer edge portions of the timing chain cover.
According to the oil seal structure disclosed in Reference 1, because the pair of mounting members extends to the left and right outer edge portions of the timing chain cover, the metallic retainer is enlarged. In addition, because the pair of mounting members of the metallic retainer is fastened to the cylinder block at the left and right outer edge portions of the cover member, a fixing position at which the left mounting portion is fixed to the cylinder block and a fixing position at which the right mounting portion is fixed to the cylinder block are greatly separated from each other. Thus, a positional displacement between the aforementioned fixing positions may increase.
A need thus exists for an internal combustion engine which is not susceptible to the drawback mentioned above.